1. Field of the Invention
This invention relates to a sealing apparatus, and a gas turbine having this apparatus. More particularly, the invention relates to a sealing apparatus for sealing clearance between assembly components which changes owing to external force or thermal expansion or the like, for example, a sealing apparatus suitable as a seal between gas turbine combustors at their outlets.
2. Description of the Related Art
Generally, a gas turbine has an air compressor (may hereinafter be referred to as “compressor”), a combustor, and a turbine as main constituents. The combustor is disposed between the compressor and the turbine connected together directly by a rotating shaft. Air to serve as a working fluid is taken into the compressor in accordance with the rotation of the rotating shaft, and compressed there. The compressed air is introduced into the combustor, and burned with a fuel. The resulting combustion gas at a high temperature and a high pressure is ejected to the turbine to drive the rotating shaft as well as the turbine rotationally. Such a gas turbine is effectively used as a drive source for a power generator or the like which is connected to the front end of the rotating shaft.
In recent years, a low NOx (premix) combustor has been used frequently from the aspect of pollution control over air pollution, etc. With the low NOx (premix) combustor, a larger amount of combustion air is needed for decreasing NOx. Thus, a sealing apparatus is applied to each part of the gas turbine to manage air leakage strictly.
Examples of the sealing apparatus used as a seal between gas turbine combustors at the outlets of the combustors are shown in FIGS. 5 to 7.
FIG. 5 shows a brush seal 102 used as a seal between gas turbine combustors at the outlets of the combustors (i.e., a side seal). The brush seal 102 comprises a rail 102a to be fitted into a groove formed in a wall portion of one of transition pipes, and a wire brush 102b whose leading end is pressed against the back of a flange portion of the other transition pipe and which is composed of wires densely planted in the rail 102a. The brush seal 102 is adapted to reduce air leakage from the casing side to the turbine side.
FIG. 6 shows a so-called worm seal 104 comprising many I-shaped punched-out pieces 104a tied in a row with the use of a flexible sheet 104b. The worm seal 104 seals clearance between flange portions of adjacent transition pipes, thereby reducing air leakage from the casing side to the turbine side. The worm seal 104 serves for sealing when it is inserted into grooves formed in the adjacent transition pipes, and a pair of arcuate projections 104ab of the worm seal 104 are pressed against the wall surfaces of the grooves under a differential pressure between the casing and the interior of the combustor.
FIG. 7 shows a sealing apparatus for sealing clearance between connecting surfaces (opposing surfaces) of the end surface of one component 106A and the end surface of other component 106B. This sealing apparatus is mounted in a space portion between groove-shaped stepped portions formed in the connecting surfaces. The sealing apparatus comprises a sealing body 107 composed of a support portion 107A having a first seal protrusion 107A1 in intimate contact with a second step surface 106A2 of the one component 106A and a second seal protrusion 107A2 in intimate contact with a second step surface 106B2 of the other component 106B, and a holding portion 107B formed to be upright on the support portion 107A; a first seal member 108 having a second side portion 108C secured to the side surface of the holding portion 107B, a curved elastic portion 108B, and an inclined first side portion 108A, the second side portion 108C, the elastic portion 108B, and the first side portion 108A being formed in the shape of a U-plate; a second seal member 109 disposed on the side surface of the holding portion 107B in symmetrical relation with the first seal member 108, having a second side portion 109C secured to the side surface of the holding portion 107B, and having nearly the same configurational requirements as those of the first seal member 108; a first seal surface 108A1 in intimate contact with a first step surface 106A1 of the one component 106A at an outward surface of an end portion of the first side portion 108A of the first seal member 108; and a second seal surface 109A1 in intimate contact with a first step surface 106B1 of the other component 106B at an outward surface of an end portion of the first side portion 109A of the second seal member 109. As noted above, end sides of the second side portions 108C and 109C are secured to the holding portion 107B. In this manner, the assembly clearance between the components where a high temperature fluid flows, or the assembly clearance between the components involving vibrations can be always sealed (see JP-A-2005-76802).
However, the seal shown in FIG. 5 has posed the problem that the deformation of the wire brush 102b at the time of combustor assembly and after operation of the gas turbine is marked, arousing a concern about deterioration of performance, so that the seal is difficult to apply to a low NOx (premix) combustor. That is, the wire brush 102b may collapse or wear when the clearance changes at the time of combustor assembly, during operational vibrations, or at start or stoppage of the gas turbine. There has also been the problem that the cost for repair of the combustor increases because of replacement work necessitated by deformation after operation.
With the seal shown in FIG. 6, higher sealing performance than that of the brush seal 102 in FIG. 5 has been confirmed. However, increases in processing man-hours and the number of the components have presented the problem of cost increases.
The sealing apparatus shown in FIG. 7 has involved the problems that an increase in the number of the components results in a cost increase, and the sealing body 107 is integrally formed, and lacks flexibility, leading to poor assembly characteristics within a narrow space.